Use of genii mpi, circuit 1, E 5-17 – Innotech Genesis II Digital Controller (v5) User Manual
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Genesis II Installation Instructions
© Mass Electronics Pty Ltd 2010
Chapter 5 – Network Installation
5-3.5.7 GENII MPI with Non-Isolated Comms.
When using a GENII MPI Modem and Printer Interface which has standard RS485 ICs, the RS485
connection is not isolated. Connecting a printer or a PC to the MPI will earth it. To prevent earth
loops all other devices on that section of Comms cable must isolate the screen from the electrical
earth.
Figure 5-17 below shows one local and three remote Genesis II non-isolated Digital Controllers, all of
which have only the four outer links fitted. In this situation it is better to fit GENII 485I Isolated RS485
Comms cards to the three remote Digital Controllers.
Figure 5-17: Use of GENII MPI, Circuit 1